741 research outputs found
Fast fluorescence dynamics in non-ratiometric calcium indicators
A fluorescence decay of high-affinity non-ratiometric Ca2+ indicator Oregon
Green BAPTA-1 (OGB-1) is analyzed with unprecedented temporal resolution in the
two-photon excitation regime. A triple exponential decay is shown to best fit
the fluorescence dynamics of OGB-1. We provide a new model for accurate
measurements of the free Ca2+ concentration and dissociation constants of
non-ratiometric calcium indicators.Comment: 3 pages, 2 figures, figures revised, added chi-square goodness of fi
Photogrammetry and ballistic analysis of a high-flying projectile in the STS-124 space shuttle launch
A method combining photogrammetry with ballistic analysis is demonstrated to
identify flying debris in a rocket launch environment. Debris traveling near
the STS-124 Space Shuttle was captured on cameras viewing the launch pad within
the first few seconds after launch. One particular piece of debris caught the
attention of investigators studying the release of flame trench fire bricks
because its high trajectory could indicate a flight risk to the Space Shuttle.
Digitized images from two pad perimeter high-speed 16-mm film cameras were
processed using photogrammetry software based on a multi-parameter optimization
technique. Reference points in the image were found from 3D CAD models of the
launch pad and from surveyed points on the pad. The three-dimensional reference
points were matched to the equivalent two-dimensional camera projections by
optimizing the camera model parameters using a gradient search optimization
technique. Using this method of solving the triangulation problem, the xyz
position of the object's path relative to the reference point coordinate system
was found for every set of synchronized images. This trajectory was then
compared to a predicted trajectory while performing regression analysis on the
ballistic coefficient and other parameters. This identified, with a high degree
of confidence, the object's material density and thus its probable origin
within the launch pad environment. Future extensions of this methodology may
make it possible to diagnose the underlying causes of debris-releasing events
in near-real time, thus improving flight safety.Comment: 26 pages, 11 figures, 3 table
ВПЛИВ ЗАНЯТЬ СПОРТОМ НА ФУНКЦІОНАЛЬНІ МОЖЛИВОСТІ СЕРЦЕВО-СУДИННОЇ СИСТЕМИ ДІВЧАТ 17-21 РОКІВ ПОДІЛЬСЬКОГО РЕГІОНУ
In this article considers the effectiveness of the impact of sports on the functionality of the cardiovascular system of girls 17-21 years old living within the Podolsk region. The function of the cardiovascular system of girls was evaluated by the ability to recover after termination of work (by the parameters of heart rate). Classes cycling and playing sports (performance of muscle work of which is connected with the mixed mode of power supply) and martial arts (performance of muscular work is associated with anaerobic (lactate) mode of power supply) contribute to improvement the functional possibilities of the cardiovascular system. This is manifested by the acceleration of recovery of heart rate after metered physical loads of 1 watts and 2 watts per 1 kg of body weight. The smallest percentage of person with a slow recovery of heart rate were detected among athletes, volleyball players and representatives of complex coordination sports. These individuals are involved in the performing of physical exercise with anaerobic (alactate) processes of metabolism.In this article considers the effectiveness of the impact of sports on the functionality of the cardiovascular system of girls 17-21 years old living within the Podolsk region. The function of the cardiovascular system of girls was evaluated by the ability to recover after termination of work (by the parameters of heart rate). Classes cycling and playing sports (performance of muscle work of which is connected with the mixed mode of power supply) and martial arts (performance of muscular work is associated with anaerobic (lactate) mode of power supply) contribute to improvement the functional possibilities of the cardiovascular system. This is manifested by the acceleration of recovery of heart rate after metered physical loads of 1 watts and 2 watts per 1 kg of body weight. The smallest percentage of person with a slow recovery of heart rate were detected among athletes, volleyball players and representatives of complex coordination sports. These individuals are involved in the performing of physical exercise with anaerobic (alactate) processes of metabolism
Theory of orbital magnetization in disordered systems
We present a general formula of the orbital magnetization of disordered
systems based on the Keldysh Green's function theory in the gauge-covariant
Wigner space. In our approach, the gauge invariance of physical quantities is
ensured from the very beginning, and the vertex corrections are easily
included. Our formula applies not only for insulators but also for metallic
systems where the quasiparicle behavior is usually strongly modified by the
disorder scattering. In the absence of disorders, our formula recovers the
previous results obtained from the semiclassical theory and the perturbation
theory. As an application, we calculate the orbital magnetization of a weakly
disordered two-dimensional electron gas with Rashba spin-orbit coupling. We
find that for the short range disorder scattering, its major effect is to the
shifting of the distribution of orbital magnetization corresponding to the
quasiparticle energy renormalization.Comment: 10 pages, 5 figure
Transitions/relaxations in polyester adhesive/PET system
The correlations between the transitions and the dielectric relaxation processes of the oriented poly(ethylene terephthalate) (PET) pre-impregnated of the polyester thermoplastic adhesive have been investigated by differential scanning calorimetry (DSC) and dynamic dielectric spectroscopy (DDS). The thermoplastic polyester adhesive and the oriented PET films have been studied as reference samples. This study evidences that the adhesive chain segments is responsible for the physical structure evolution in the PET-oriented film. The transitions and dielectric relaxation modes’ evolutions in the glass transition region appear characteristic of the interphase between adhesive and PET film, which is discussed in terms of molecular mobility. The storage at room temperature of the adhesive tape involves the heterogeneity of the physical structure, characterized by glass transition dissociation. Thus, the correlation between the transitions and the dielectric relaxation processes evidences a segregation of the amorphous phases. Therefore, the physical structure and the properties of the material have been linked to the chemical characteristics
On the Application of a Monolithic Array for Detecting Intensity-Correlated Photons Emitted by Different Source Types
It is not widely appreciated that many subtleties are involved in the
accurate measurement of intensity-correlated photons; even for the original
experiments of Hanbury Brown and Twiss (HBT). Using a monolithic 4x4 array of
single-photon avalanche diodes (SPADs), together with an off-chip algorithm for
processing streaming data, we investigate the difficulties of measuring
second-order photon correlations g2 in a wide variety of light fields that
exhibit dramatically different correlation statistics: a multimode He-Ne laser,
an incoherent intensity-modulated lamp-light source and a thermal light source.
Our off-chip algorithm treats multiple photon-arrivals at pixel-array pairs, in
any observation interval, with photon fluxes limited by detector saturation, in
such a way that a correctly normalized g2 function is guaranteed. The impact of
detector background correlations between SPAD pixels and afterpulsing effects
on second-order coherence measurements is discussed. These results demonstrate
that our monolithic SPAD array enables access to effects that are otherwise
impossible to measure with stand-alone detectors.Comment: 17 pages, 6 figure
Surface alignment and anchoring transitions in nematic lyotropic chromonic liquid crystal
The surface alignment of lyotropic chromonic liquid crystals (LCLCs) can be
not only planar (tangential) but also homeotropic, with self-assembled
aggregates perpendicular to the substrate, as demonstrated by mapping optical
retardation and by three-dimensional imaging of the director field. With time,
the homeotropic nematic undergoes a transition into a tangential state. The
anchoring transition is discontinuous and can be described by a double-well
anchoring potential with two minima corresponding to tangential and homeotropic
orientation.Comment: Accepted for publication in Phys. Rev. Lett. (Accepted Wednesday Jun
02, 2010
Spin susceptibility in superconductors without inversion symmetry
In materials without spatial inversion symmetry the spin degeneracy of the
conduction electrons can be lifted by an antisymmetric spin-orbit coupling. We
discuss the influence of this spin-orbit coupling on the spin susceptibility of
such superconductors, with a particular emphasis on the recently discovered
heavy Fermion superconductor CePt3Si. We find that, for this compound (with
tetragonal crystal symmetry,) irrespective of the pairing symmetry, the stable
superconducting phases would give a very weak change of the spin susceptibility
for fields along the c-axis and an intermediate reduction for fields in the
basal plane. We also comment on the consequences for the paramagnetic limiting
in this material.Comment: 10 pages, 3 figure
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